Heartbeats at the Speed of Light
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Scientists hope that this type of nonintrusive method can help uncover more about cardiac development and the unknown causes of congenital heart disease. “We can use it to noninvasively study how environmental changes that change the heart rate might lead to heart defects,” Jenkins says. “Or to study how changes in the heart rate during crucial stages of growth might change gene expression.”
Jenkins can’t yet explain how the light causes the heart muscle to contract, and says that it may take years to figure this out. But he thinks it may be that the infrared wavelengths are heating up the cells, somehow changing the ability of a particular set of ion channels to transmit a charge.
Douglas Cowan, an assistant professor at Children’s Hospital in Boston, has been working on a different method for stimulating heart muscle function, one based on tissue engineering. He posits that Jenkins’s approach might help nudge stem cells to differentiate into beating cardiac cells.
Because light waves can’t get through more than a few layers of tissue, the researchers suggest that, in humans, their technique might be particularly useful for pacing an exposed heart during surgery.
Beyond that, an implanted optical pacemaker–while still a far-off prospect–is an idea that many researchers believe is worth pursuing. “In kids, electric pacing for 15 or 20 years causes the heart not to develop so well,” Jenkins says. While this is less worrying for a 75-year-old, it can be a big concern for a pediatrician who’s putting a pacemaker into a three-year-old. “If optical pacing were able to pace the heart in such a way that it beats more intrinsically, that could be an advantage,” he says.
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